No error when asking for non-existant page

When I type in a url that doesn’t exist, it just displays the home page for request url.

I’ve just installed a fresh copy on https://www.alamedahomesforsale.net. If I type in https://www.alamedahomesforsale.net/kjahdsflashjd, it will display the home page instead of a 404 error page. I have other wp installs in sister directories that are working correctly, i.e. it returns the 404 error page.

Any thoughts? Thanks.

Ben.